Alkaline detergent composition



United States Patent Office 3,484,379 ALKALINE DETERGENT COMPOSITION Abraham Mankowich, Bel Air, Md., assignor to the United States of America as represented by the Secretary of the Army No Drawing. Filed Nov. 30, 1965, Ser. No. 521,475 Int. Cl. Clld 3/066 US. Cl. 252-137 9 Claims ABSTRACT OF THE DISCLOSURE An alkaline detergent composition for removing asphalt soil consisting essentially of an amphoteric surfactant of a quaternary imidazolium hydroxide structure; an anionic surfactant of the alkylaryl sulfonate type together with a mixture of alkali metal metasilicates, and phosphates adjusted to a pH of about between 11.8-12.2.

This invention relates to a novel alkaline detergent composition characterized by the fact that it is capable of removing asphalt soil. The invention pertains more specifically to improved detergency in a soak type cleaner embodying a more effective combination of synthetic surface active agents and alkaline detergent salts.

Although a wide variety of alkaline cleaners have been available for cleaning steel and other resistant metals to leave the surface in the requisite clean condition for electroplating, painting, enameling, etc., previous alkaline cleaners have not been effective removers of asphalt soil. The successful application of any protective or decorative finish depends largely on how well the metal surface has been cleaned prior to the coating process. Any amount of asphalt, grease, or mineral oil contamination which resists the conventional alkaline soak and adheres to the surface will contribute adversely to any coating process.

In metal cleaning, organic solvents and mixtures containing certain improvers are resorted to for dissolving asphalt and other hydrocarbon residues; the organic solvent cleaning is often accompanied by scrubbing, rubbing or other mechanical treatment to remove resistant residues. The use of organic solvents also leaves a hydrophobic film on articles being cleaned, which must be removed in a subsequent aqueous cleaner to obtain adhesion of electroplating, paint, enameling, etc.

The primary object of the present invention is to provide an improved alkaline detergent composition which possesses unusual detergency and is singularly effective as a soak cleaner for penetrating and suspending the most resistant soil.

Another object of the invention resides in the specific combination of surface active agents, or surfactants, and certain alkaline detergent salts in solution in order to impart to the latter effective detersive action for removing asphalt from surfaces rapidly and completely.

Briefly, effective deterengcy in accordance with the invention is attained by employing a composition consisting essentially of an amphoteric surfactant of a quaternary imidazolium hydroxide structure and an anionic surfactant of the alkyl aryl sulfonate type together with a mixture of alkaline detergent salts. The specific amphoteric and anionic surfactants are used in accordance with the invention in a suitable alkaline solution at pH 12, the desired alkalinity being provided by alkali phosphates and metasilicates. Since an amphoteric surfactant acts anionically in an alkaline solution, the effective detergency demonstrated by the present admixture of amphoteric and anionic agents is essentially that of two anionicallyacting surfactants.

The amphoteric surfactant which is employed in the 3,484,379 Patented Dec. 16, 1969 present composition is represented by the following quaternary imidazolium structure:

t? 112C O-R NaO CHtCHr-N-OHzC OONa in which R is an alkyl radical, preferably of 9 or 11 carbon atoms. The undecyl compound] is a lauric acid derivative, identified as l-(2-sodium acetato) 1-(2-sodium ethylato) 2-undecyl 4,5-dihydroimidazolium hydroxide. The unde'cyl structure is also representative of the coconut derivative sold under the name Miranol CM, which is also an equally effective surfactant for the present composition. Similarly, the nonyl compound derived from capric acid is a suitable surfactant for the purposes of this invention, designated as 1-(2-sodium acetato) l- (2-sodium ethylato) 2-nonyl 4,5-dihydroimidazolium hydroxide, and this product is commercially available as Miranol SM. These and other quaternary imidazolium hydroxides and the method for making them are disclosed in US. Patent 2,528,378.

The anionic surfactant which is employed in the composition is of the alkyl aryl sulfonate type represented by the formula:

RSO3M wherein R is an alkyl group containing about 10 to 18 carbon atoms, and M is an alkali metal, such as sodium or potassium. Among the most effective surfactants of this type is sodium dodecylbenzene sulfonate, which displays highly beneficial results in combination with the quaternary amphoterics mentioned above. Equally effective are mixtures of alkyl aryl sulfonates in which the alkyl group has chain lengths of about 10 to 18 carbon atoms.

The desired alkaline detergent properties of the composition are provided by alkali metal metasilicates and phosphates, and more specifically, by an admixture of sodium metalsilicate, primary sodium phosphate and trisodium phosphate, blended in a weight ratio that maintains the optimal pH 12 of the soltuion. The inclusion of the primary sodium phosphate provides a means for adjusting the alkalinity of the composition. If desired, a portion or all of this salt may be replaced by a salt of low alkalinity, for example, secondary sodium phosphate (shown in Example II).

In the actual practice of the invention, the alkaline detergent composition is prepared in solid form, more desirably as a dry powder mixture consisting esesntially of from about 14 percent to about 24 percent by weight of an admixture of a quaternary imidazolium hydroxide and an alkyl aryl sulfonate, the Weight ratio of said quaternary imidazolium hydroxide to said alkyl aryl sulfonate being in the range of between 1.3 to 1 and 2.3 to 1, respectively.

The following specific examples are intended to illustrate more fully the nature of the invention but are not to be regarded as limiting the scope thereof.

EXAMPLE I An alkaline detergent composition was prepared in accordance with the invention using anhydrous alkaline salts adjusted to a pH 12 in solution Sodium dodecylbenzene sulfonate 9.3

A solution was formed containing the above composition in a concentration of about 4.82% on a Weight to volume basis. The solution was then brought to a boil. The solution was then utilized in an actual cleaning operation involving steel test panels which were polished with a No. 1 emery cloth, cleaned in acetone, rinsed with absolute ethyl alcohol and dried. The test panels were then coated with a petroleum asphalt conforming to Federal Specification SS-706, grade 85l00, designation AP3. The panels were then immersed in the boiling solution and allowed to stand therein for about minutes. At the end of that period, the panels were removed from the solution, rinsed with water and examined for the extent of cleaning. The asphalt coating was completely removed, and the surface appeared to be free of all surface film.

4 capryl 4,5-dihydroimidazolium hydroxide (Miranol SM) and sodium dodecylbenzene sulfonate along with alkaline detergent salts, was labeled Solution A. Two other 8% solutions, which contained the above surfactants singly, were labeled Solution B and Solution C.

Steel test panels prepared as in Example I were initially weighed and then coated with a petroleum asphalt conforming to Federal Specification SS-A706, grade 85l00, designation AP-3. The asphalt was spread evenly on one face of the test panels. Coated panels were immersed in boiling solutions A, B and C, and they were allowed to remain therein for a designated period of time. They were then withdrawn, rinsed with water and allowed to dry. The panels were then reweighed to determine the amount of residual soil. The results are given in Table I below.

TABLE I Percent Concentration, Weight to volume Contact Percent Time, Asphalt NazSiOzbHzO NaIIzP 0+Hz0 Na PO4-12H 0 Miranol SM Trepolato 1 -95 minutes Removed EXAMPLE II 25 The above results show the effectiveness of the present The following composition indicates a modification within the purview of the present invention.

Ingredient: Percent by weight Sodium metasilicate, Na SiO 32.8 Secondary sodium phosphate, Na HPO 25.7 Trisodium phosphate, Na PO 18.1 Undecyl quaternary imidazolium 14.1

The present composition may be used at various concentrations depending on the ingredients used and also on the extent of the asphalt contamination to be removed. When anhydrous alkaline salts are employed (as in Examples I and II), the soak solutions formed are used to better advantage when the alkaline detergent composition is dissolved in water to give a concentration of about 4.5 to about 5.1 percent on a weight to volume basis.

The temperature of the solution is more desirably maintained above C. and preferably at a boil. Nonferrous metals may be cleaned because the solution contains sodium metasilicate, a corrosion inhibitor. Although lower temperatures are operable, there is an increase in the cleaning time.

Hydrated alkaline detergent salts are advantageously employed in the composition, especially as dry powder ingredients. The following specific examples show preferred embodiments utilizing hydrated salts.

EXAMPLE III Sodium dodecylbenzene sulfonate Ingredient: Percent by weight Sodium metasilicate pentahydrate, Na SiO -5H O Primary sodium phosphate monohydrate, NaH PO 'H O T risodium phosphate dodecahydrate, Na PO -12H O Coconut imidazolium hydroxide, Miranol Sodium dodecylbenzene sulfonate composition which utilizes a quaternary imidazolium compound and an alkyl aryl sulfonate as surfactant admixture. The absence of alkyl aryl sulfonate surfactant (Solution B) diminished the effectiveness of the solution cleaner with 49% of the asphalt remaining on the panel, even after 21 minutes of immersion cleaning at a boil. The absence of the quarternary imidazolium compound results in a less effective asphalt remover (Solution C), as noted in the table above. The presence of a single detergent in Solutions B and C was not effective for removing asphalt, but the novel admixture of surfactants displays considerable improvement, both in the amount of asphalt soil re moved and with the speed with which 100% asphalt removal is attained. It is significant that While Solution C removes of the soil, the cleaner is worthless because the residual 10% of soil makes subsequent electroplating, painting, or enameling impossible.

Though the optimal pH 12 provides a solution of moderate alkalinity and is to be preferred, a slight pH range of, for example, 11.8-12.2 is still effective for the purposes of the present invention.

The term asphalt as used herein and in the claims is intended to include any bituminous substance, solid-toplastic hydrocarbon residues, tarry substances, mineral pitch and combined with mineral matter, soil and grime.

The specific examples and details disclosed herein do not represent the limits of this disclosure, and it is intended that the protection afforded shall extend to the full spirit and scope of this invention as defined by the claims.

I claim:

1. An alkaline detergent composition for removing asphalt soil consisting of:

(a) an amphoteric surfactant represented by the structural formula:

I-Iz(|3I| ,T H2O /CR NaO OIIzC1-Iz l\, -CII2C o ONa wherein R is selected from an alkyl group consisting of 9 to 11 carbon atoms, and an anionic surfactant represented by the structural formula:

wherein R is an alkyl group of about 10 to 18 carbon atoms and M is selected from the group consisting of sodium and potassium, the weight ratio of said amphoteric surfactant to said anionic surfactant being in the range of between 1.3 to 1 and 2.3 to 1, respectively, and

(b) from about 76 percent to about 86 percent by weight of an admixture of inorganic alkaline detergent salts selected from the group consisting of alkali metal metasilicates and primary and tri-alkali metal phosphates and adjusted to provide a pH of between 11.8 to 12.2 in solution.

2. An alkaline detergent composition in accordance with claim 1 in which said amphoteric surfactant is:

3. An alkaline detergent composition in accordance with claim 1 in which said amphoteric surfactant is:

H2C *"-N NaO CHzCHg-N-O H 0 0 O Na 4. An alkaline detergent composition in accordance with claim 1 in which said anionic surfactant is sodium dodecylbenzene sulfonate.

5. An alkaline detergent composition in accordance With claim 1 in which said alkaline salt admixture consists essentially of about 36.7 percent sodium metasilicate pentahydrate, about 35.5 percent trisodium phosphate dodecahydrate and about 12.8 percent primary sodium phosphate monohydrate, said percentages being by weight of said composition.

6. An alkaline detergent composition for removing asphalt soil consisting essentially of:

Percent Ingredient: by weight Sodium metasilicate pentahydrate 34.5 Primary sodium phosphate monohydrate 12.0 Trisodium phosphate dodecahydrate 33.5

H ON

H2O OCnH2s NaO CHzCHr-N-CH2C 0 ONa Sodium dodecylbenzene sulfonate 6.0

7. An alkaline detergent composition in accordance with claim 6 which includes sufiicient water to form a solution comprising from about 7 percent to about 8.5 percent of said composition on a weight to volume basis.

8. An alkaline detergent composition for removing asphalt soil consisting essentially of:

9. An alkaline detergent composition in accordance with claim 8 which includes suflicient Water to form a solution comprising from about 4.5 percent to about 5.1 percent of said composition on a weight to volume basis.

References Cited UNITED STATES PATENTS 3,118,842 1/1964 Besser 252--152 3,216,945 11/1965 Mankowich.

OTHER REFERENCES Detergents and Emulsifiers, 1963 Annual, McCutcheon, p. 92.

LEON D. ROSDOL, Primary Examiner M. HALPERN, Assistant Examiner US. Cl. X.R. 

